Pyroelectric vidicon tubes offer certain advantages in terms of cost and simplicity over conventional vidicon tubes and infrared viewing devices currently in use. The target material has limitations with regard to sensitivity and response time at present, but materials research could provide a breakthrough in these areas at any time. The outstanding difficulty in that the pyroelectric effect is an ac phenomenon, i.e. the target is electrically polarized only in response to a change in radiation. To view a still scene or image it is necessary to either chop the incident radiation with a shutter or scan the image with a moving mirror before it strikes the target material. The success of the latter method depends on the rate of displacement of the scene and this together with the size and resolution capabilities of the target determines the minimum displacement of the mirror.
This displacement is reproduced in display device, which may be a commercially available TV set, and can be very distracting to the viewer. A simple method of removing it is to place the screen of the TV set adjacent the back surface of the mirror and view the display's reflected image as the mirror rotates. Unfortunately this results in a very bulky arrangement of the system and further is impractical where remote viewing is desired. A better method is disclosed in Pat. Application Ser. No. 663,033 to John T. Hall for "Electronic Motion Compensation for the Pyroelectric Vidicon," filed Mar. 2, 1976. This application also discloses other details of the vidicon system which are not considered essential for understanding the present disclosure.